Method for cementing wells



Sept. 14, 1954 L E ETAL 2,689,008

METHOD FOR CEMENTING WELLS Filed June 15, 1951 FIG. I. INVENTOR. Thomas 0. Allen,

By John C. Mc Duffie J11,

Patented Sept. 14, 1954 F F ICE METHOD FOR CEMENT-DIG WELLS Thomas '0. Allen and John 'CfiM'c'D'uiiie, Jr., B'e1l'- sire, Tex., a'sSignors, by mesne assignments, to Standard Oil-Development Company,- Elizabeth; N. J a corp'orationof Delaware Application June 15, 1951, Serial No, 231,852

'6 Claims.

"The present invention relates to a process for cementing wells. More particularly, the invention "relates to a method T01" squeezing cement train a wen here into a "formation adjacent thereto.

"The present invrition may'be described. briefly fas iii vdlying 'a method for cementing a wen in which a body 6f a cementitious material is loeatedina well here adjacent a formation to be sealed. A shok wave or waves is then generated in the "body or the cementitious material which "results in the 'eeinerititious material being forced into the "producing fermation, the effect of the high pressure shock wave of waves being to dehydrate rapidly "the 'cementitious material when a hydraulic e'ementi's employed and toca'us'e substantreny a "flash "setting the-rent.

v The 'sl'iocl i wave empmyea in the practice (if the 'present inventi'on may be generated by disch'arg'ing a high explosive in 'the well bone at a point above the formation to 'be sealed. Usually the-hi-gh'exn1osi'vewi1l be detonated Or discharged when in the *body or the eementitiqus material itse'l ffbut it is edntempiated that the explosive may he placed in a fluid "media ineludin'g fluid eementitious imaterfal In short, it is' :eontemplated that the' body "of new cementitious material may be: li'll':ate ':l adjacent the producing formation an the well substantially completely filled with afluid media such as drilling fluid "whitihmay be a suspension or solidsin an aqueous nr dily mediar We "prefer to generate 'a high pressure shock wave in the welrbe're by detonating a high exp'los'iv e inth'e eem'eiiti'tious 'b'ody above the point to be sealed or the Well fluids above the formatron to be sealed. The high explosive may "be" of any type, su'h a-s -pento1'ite; tetryl, 'T-NT and ether weuhigh explosives and may he augmented byany suitably chosen booster explosive material; Fo example, tetryl cou' ld ib'emsed as asuitahle- "booster for' pen-tolite, since portiondf the high explosive. "Thetype 0f apparatusto 'be employed 'w'hen'using shaped charges will be described in further detail hereinafter.

'The 'cement'i'tious riia'terial employed in the practice (if the present invention may suitably neanynmune cemefitsueh as Portland cement, either of the normal type or slow setting cement. "The hydraulieieeinent may also be an anhydrous cement such as thetype known on the market'asC'al-Seal. The cementi'tious material "may also be a 'thermosetting plastic, such as a resir'ious' material of the phenel-formaldehyde type. 'Other thermosetting' plastic materials such as urea-'formaldehyde's and melamine-formalde- "h'ydes may be used as the 'cementitious' material in lieu of hydraulic cement. Ordinarily, 'however, we "will refer to use a hydraulic cement rather than a therr'nosetting plastic but some 'eonditiohs'will make the use er the latter preferable In 'praneing' the present invention the desired eemennneus" material, such a thermosettin'g plastic "or cement, would be placed in the well 'at'a p'rdper'depthto "sever the area to be sealed with "a 'sufiic'i'ent quantity 30f material employed to create an excess of "sealing "material "standing -above the areate'be sealed. Sealing materials may be .pl'aced by conventional "techniques, 'sueh as "by use o fa dumpbaile'r or circulation. The "cbnt'ainer "or tool in which the high explosive is arranged or in which the materialused to generate "the shoek Wave is employed would then be runonpipeor on'awire line -to a'pbint within the bore 'abovethe top 0f the sealing material. 'sub'sequent "detonation-or'diseharge of the explosi'x'ie -creates high pressure gases resulting in 'a shock wave"whichfforces the sealing'material in the formation *or through perforations when a cased well bore is treated.

mentioned before, it is preferred to use-a shaped charge in generating the-high pressure ehoek wave since the shaped charge has-the partie'u'lar advantage of *a' directional explosion by pos'itioningthetool eontainingthe shaped charge above the area'to' be cemented. cif the high pressure gasesgeneraited by detonation are directed downwardly in the well bore thus causing temporary eo'fifinemeht and compression of the sealing material belbw the 11061 from "which the to sealing material er eeinentitieus material "could 3 only escape into the permeable earth formations or through the casing or liner perforation openmgs.

Furthermore the use of a hydraulic cement for a sealing material enhances the advantages of the explosive squeeze tool of the present invention because the high pressures generated by detonation of an explosive charge causes dehydration of the cement adjacent to the formation as well as forcing the cement into the formation or casing perforations. Effective dehydration by high pressure gases from an explosion results in an effective seal because dehydration is accomplished in a substantially faster operation than ordinarily by virtue of the pressure generated by the high explosive being detonated in the well bore resulting in a shock wave therein.

The invention will be further illustrated by reference to the drawing in which Fig. 1 shows an arrangement of apparatus in a perforated cased. well bore with a body of fluid cementitious material arranged therein prior to the generation of the high pressure shock wave;

Fig. 2 is a detail of apparatus employed for generating a shock wave in the well bore;

Fig. 3 shows an arrangement of apparatus prior to shooting in a permanent type well completion arrangement; and

Fig. 4 shows the condition of a well after detonation of a high explosive therein and generation of a shock wave in the fluid cementitious material.

Referring now to the drawing in which similar numerals will be employed to designate identical parts, numeral ll designates a cased well bore which has been cemented by setting of cement around the casing as indicated by numeral l2. The cased well bore penetrates a producing formation [3 which it is desired to seal and which has been perforated by a suitable gun perforator. As will be seen the casing H has been perforated at a plurality of points indicated generally by numeral [4.

Arranged in the casing H by conventional well-known techniques, such as by circulation or by a dump bailer, is a body of fluid cementitious material I5. Above the body of fluid cementitious material and extending substantially to the well head substantially completely filling the well is a body of a fluid medium l6 which may be a drilling fluid either of an aqueous or an oily base. Suspended from the well head, not shown, by a wire line or an electric cable I1 is a container or tool [8 which is shown more clearly in Fig. 2. This container or tool l8 may have arranged therein a high explosive. A high explosive I9 is a shaped charge and is confined in tool [8 by a conical wall member 20 constructed of a suitable material which may be a ferrous or non-ferrous metal. The function and use of shaped charges are well known and further details of the jetting, exploding action thereof will not be given here since a discussion thereof will be found in the literature such as in the patent to Muskat et al., 2,494,256. The tool I8 is suspended by means of wire line H which may suitably be an electrical cable which acts as a suspending means and also as means for providing electrical energy to detonator 2| which may be of a well known type which serves to fire electrically the high explosive IS in the tool I8.

Referring now to Fig. 3, it will be seen that the casing I I has been cemented by cement 12 in the well bore andthat a plurality of perforations I4 have been formed in casing II by a gun perforator as is well known. Similarly, as in Fig. 1, a body of cementitious material l5 has been arranged in the casing II and a container or explosive tool [8 lowered down the well bore from the well head 25 as will be described further. In this embodiment of our invention a tubing 26 is arranged in the well bore above a formation l3 which is to be sealed or cemented.

The wire line or electric cable l1 extends to the well head 25 through the usual valve equipment and control apparatus indicated generally as 28. Arranged above the control apparatus 28 and above the T connection 29 which connects to the tubing 26 is a pipe 30 provided with a stuffing box 3| through which the wire line or cable [1 extends to reel or drum 32 which suitably may be arranged in a service truck 33. Connections 34 to tubing 26 allow the well fluid such as crude petroleum to be routed therethrough to gas separator 35 and lease tank 36.

Referring now to Fig. 4, the condition of the cased well bore II immediately after the shooting is shown. The shaped charge IS in the tool l8 has been detonated'which caused generation of a high pressure shock wavein a body of cementitious material 15 which caused the cementitious material [5 to be forced out through the perforations l4 into the producing formation 13 as indicated generally by numeral 40 causing a substantial sealing of the formation I3 from the formation 21. The'tool l8, if it has not been destroyed by the rapid generation of gases, may then be retrieved by reeling up the wire line or removal of cable 11 on drum 32.

The mode of operation of the'apparatus illustrated in Figs. 1 to 4 is substantially as follows:

As mentioned before the body of cementitious material is located in the well bore adjacent the formation or in the region of or adjacent the perforations to be sealed. A tool or container containing a high explosive or a material which will generate a high pressure shock wave is then lowered into the well bore on a wire line or electric cable. The high explosive is then discharged and the material which-is used to generate the shock wave is caused to expand to generate gases as has been described before to cause rupture of the container. Assuming that a high explosive shaped charge is employed ases are rapidly generated which causes rapid dehydration and forcing of the cement into a producing formation to be sealed or through perforations into a formation to be sealed. The rapid expansion of gases serves to lift the column of drilling fluid in the well bore above the point where the explosive is discharged, causing displacement of a portion of the drilling fluid from the well bore. The amount displaced is not large, however, and the remainder of the drilling fluid in the well then drops back and exerts a hammer effect on the cement in the well bore and that which has been displaced into the formation treated. In effect then, a dual action is obtained in our invention: the high pressure shock wave serves to displace the cement into the formation and dehydrate same in place and the hammer of the descending column of well fluid causes further squeezing of cement, insuring complete filling of voids and crevices. Thereafter the tool employed to cause rapid setting of the cement or cementitious material is then withdrawn. The well treated, as described, may then be further serviced or operated. a

As seen from the foregoing description taken with the drawing the inventionis notlimited to cementing in cased boreholes but may suitably li e-fused anopenborehole;i- It is possible in accordance withthe practice of our invention to generate a highpressure sl'iock w'ave in cementitious material=.;:of the typesmentioned before i which will cause rapid settingof the cementitious material in the perforationsor inthe formation. Thisrapidsetting of the cementitious material leaves the excessaof? tlier cementitious material in. thewell bore. inia fluid. condition. Itmaybe desirable-to removesuclr excess fluid-cementitious material which.- may be: done by conventional means, such as by bailin or by circulation.

The invention is also susceptible to obtaining very tight seals in formations which it is desired to seal off from the well bore. For example, by virtue of the high pressure shock waves the cementitious material when the pressure of the shock wave is sufliciently great and the permeability of the earth formation is sufficiently high causes displacement of cement into the formation. This may be in the form of filling pore voids a relatively short distance from the well bore. It is specifically contemplated that the high pressure shock wave may cause hydraulic fracturing of the formation along formation bedding planes or native formation fractures resulting in the cement being displaced a considerable distance from the well bore by the high pressure shock wave.

In the detonation of high explosives in accordance with the present invention in a well bore to cause cementing in perforations or formations, the detonation of the high explosive generating high pressure gases in the cementitious material will initiate a shock wave therein. This wave moves sealing material or cementitious material into any available openings, such as perforations or pore voids in the face of permeable formations where the desired sealing or cementin is to be effected. Since the cementing material has previously been located over the interval of the formation to be cemented or sealed the effect of the shock wave is to insure complete filling of openings by pressure difierential or squeeze from the well bore to the formation.

The present invention is not to be limited to the particular examples which are given by way of illustration and not by way of limitation. For example, a plurality of shots may be desirable where it is desired to seal or cement a plurality of formations or to discharge high explosives in sequence to cause build up or setting of layers of cementitious material in perforations or in formations. For example, a plurality of tools, such as shown in Fig. 2, may be spaced at intervals along wire line I! and each of the tools containing a high explosive may be detonated in sequence with the lower being exploded first and the subsequent charges being exploded sequentially going up the well bore.

The invention may be used in building up desired seals or used in cementing operations in stages where fracturing occurs easily in formations, of great permeability. The invention may also be used in building up a sheath around a well bore thereby plugging formation voids, fractures, and crevices in combatting lost returns in drilling operations.

It may be seen from the foregoing description that the invention is broadly directed to locating a body of cementin a well bore and generating in said body of cement a shock wave which causes dehydration of the cementitious material and setting of the cement in bore voids and crevices adjacentto the well bore.

It is", therefore, intended" that v the invention. is broadlydirected to such operationsf Y Thenatureand -objects of the present invention havingbeen-completely described and illustrated, what we wish to claim as new and-useful and to secure by Letters Patent is:

1. A methodfbrcementing'a wellhaving'a perforated casing. therein. which comprises locating a body of hydraulic cementitious material. in, said perforated casing in the. region of, and. adjacent said perforations, locating a higheexplosive. detonat'ing. charge in the body of. cementitious material, and dischargingsaid charge and forcing at least a portion of said cementitious material through the perforations, thereby dehydrating and setting said portion of cementitious material to seal the perforations.

2. A method for cementing a well having a perforated casing therein which comprises locating a body of hydraulic cementitious material in said perforated casing in the region of and adjacent said perforations, locating a high explosive detonating charge in the body of cementitious material, discharging said charge and forcing at least a :portion of said cementitious material through the perforations, thereby dehydrating and setting said portion of cementitious material to seal the perforations, and removing excess remaining cementitious material from said casing after discharging said charge and before said excess cement has set.

v 3. A method for cementing a well having a perforated casing therein which comprises locating a body of fluid hydraulic cementitious material in said perforated casing in the region of and adjacent said perforations, locating a downwardly directed high explosive detonating charge in the body of cementitious material, discharging said charge and forcing at least a portion of said cementitious material through the perforations, thereby dehydrating and setting said portion of cementitious material to seal the perforations.

4. A method in accordance with claim 3 in which the downwardly directed explosive charge is a shaped charge.

5. A method for cementing a well having a perforated casing therein which comprises locating a body of fluid hydraulic cementitious material in said perforated casing in the region of and adjacent said perforations, locating a high explosive detonating shaped charge in said body of cementitious material above said perforations, discharging said charge and forcing at least a portion of said cementitious material through the perforations, thereby dehydrating and setting said portion of cementitious material to seal the perforations and removing excess fluid cementitious material from said casing after discharging said charge.

6. A method for cementing a well having a perforated casing therein in which a column of fluid media is arranged substantially filling said well which comprises locating a body of fluid hydraulic cementitious material in said perforated casing in the region of and adjacent said perforations below the column of fluid media, locating a downwardly directed high explosive detonating shaped charge in the body of cementitious material above said perforations, discharging said charge and forcing at least a portion of said cementitious material through the perforations, the discharge of said charge lifting the column of fluid media in said well and then dropping 7 same ,on said cementitious material, thereby dehydrating and setting said portion'of said .cementitious material to seal the perforations, and then removing excess remaining fluid cementitious material from said casing after said fluid media has been lifted and dropped.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,588,643 Alexander June 15, 1926 1,734,670 Greene Nov. 5, 1929 1,843,002 Small Jan. 26, 1932 1,856,912 Grebe et a1 May 3, 1932 8 Number Name Date 2,072,982 Dale .'1 Mar. 9, 1937 2,494,256 Muskat et a1 Jan. 10, 1950 A 2,591,807 -Greene Apr. 8, 1952 -FOREIGN PATENTS Number Country Date 28,030 Great Britain of 1911 OTHER REFERENCES The 011 Weekly, May 22, 1939, Seleetive Exclusion of Fluids from Wells. by P. D. Torrey, pages 26, 27, 28, 30, 32, 34, 35; page 30 most pertinent. 

1. A METHOD OF CEMENTING A WELL HAVING A PERFORATED CASING THEREIN WHICH COMPRISES LOCATING A BODY OF HYDRAULIC CEMENTITIOUS MATERIAL IN SAID PERFORATED CASING IN THE REGION OF, AND ADJACENT SAID PERFORATIONS, LOCATING A HIGH EXPLOSIVE DETONATING CHARGE IN THE BODY OF CEMENTITIOUS MA- 